The present invention relates generally to electropneumatic (“EP”) brake control valves and, more specifically, to a relay valve for use in an electropneumatic train.
Electropneumatic brake control valves are well known in the passenger railroad art and the mass transit railroad art. Because the trains are short and are not involved generally in a mix and match at an interchange of different equipment, the ability to provide pneumatic and electrical control throughout the train has been readily available in the passenger and the mass transit systems. In freight trains, the trains may involve as much as 100 cars stretching over one mile or more. The individual cars may lay idle in harsh environments for up to a year without use. Also, because of the long distance they travel, the cars are continuously moved from one consist to another as it travels to its destination. Thus, the use of electropneumatic-pneumatic valves in the freight trains has been very limited.
Recently, the American Association of Railroads (“AAR”) has been testing and experimenting with the incorporation of electropneumatic valves on the cars of a freight train. Various systems exist in the industry for adaptation of existing pneumatic brake control valves, as well as standalone electropneumatic brake control valves.
An example of an adaptation of a standard AAR brake control valve is illustrated in U.S. Pat. No. 5,393,129 to Troiani et al. Troiani et al. provides an overlay at the connection of the pneumatic system to the pipe bracket. An electropneumatic valve system is connected to the emergency reservoir between the retainer port of the pipe bracket and the retainer. The service valve portion remains in its release position, which allows transmission of the brake control signal from the electropneumatic brake control valve through the service portion to the brake cylinder.
Various configurations of electropneumatic brake control valves mounted to a standard pipe bracket are illustrated in U.S. Pat. No. 6,325,464 to Truglio et al.
Although the technology for electropneumatic brake control valves has been implemented and accepted, there is still a cost factor in installing an electropneumatic-controlled device on each railroad car.
The present disclosure provides a relay valve configuration as a pneumatic brake control valve which can be used with various cars in an electropneumatic train and under the control of one of the electropneumatic brake control valves. This reduces the number of electropneumatic brake control valves. The improved brake control valve includes a relay valve mounted at an interface of the manifold. The valve has a source inlet connected to the reservoir interface port, an inlet connected to atmosphere, an outlet connected to the brake cylinder interface port and a control inlet connected to the exhaust interface port. The valve is responsive to the control inlet connected to the exhaust interface port to selectively connect the brake cylinder interface port either to the reservoir interface port or atmosphere. The exhaust interface port in AAR is known as the retainer port. A check valve/choke is also mounted on the manifold at the interface and is in the same housing as the relay valve.
Also, connected to the manifold is a bypass plate or a vent valve structure, which includes a passage connecting the two brake cylinder ports, which are normally used for the emergency brake portion.
In the brake system for a train, there are at least two brake control valves. At least one of the valves is the pneumatic brake control valve, including the relay valve previously described. A pipe connects the brake cylinder port of the first brake control valve to the exhaust port of the second control valve so as to control the vent valve with the brake cylinder pressure. The first brake control valve is an electropneumatic brake control valve. The train may include a plurality of brake control valves, including the vent valve previously described, and a single electropneumatic brake control valve can control more than one of the second style brake control valve through its exhaust port.
These and other aspects of the present disclosure will become apparent from the following detailed description of the disclosure, when considered in conjunction with accompanying drawings.